A high-fat “western” diet weakens the ability of the immune system to fight infectious disease particularly in the gut, leaving people more at risk of food poisoning, according to researchers at University College Cork (UCC).

A high-fat “western” diet weakens the ability of the immune system to fight infectious disease particularly in the gut, leaving people more at risk of food poisoning, according to researchers at University College Cork (UCC).

This kind of diet leaves people more prone to illness from listeria, a type of bug that can cause food poisoning when eaten.

It can live and grow in a wide range of foods, in particular chilled ready-to-eat foods such as packaged sandwiches, butter, cooked sliced meats, smoked salmon, certain soft cheeses and pate.

APC Microbiome Ireland scientists based at UCC found that feeding mice with a “westernised” diet, which is high in fat and low in fermentable fibre, affected both the immune system and the bacteria resident in the gut.

Even short-term consumption of the high-fat diet was found to increase the number of goblet cells in the gut, which are the target for infection by listeria, as well as causing profound changes to the microbiota composition and immune system.

The high-fat diet also raised susceptibility to infections beyond the gut.

The researchers said the increased human consumption of a ‘westernised’ diet has been linked to the dramatic rise in conditions such as obesity and type 2 diabetes.

Research has shown the direct effects of dietary fats upon both the immune system and the gut microbiota.

Listeria can cause serious disease, particularly in pregnant women, the elderly and people whose immune systems are weakened.

“Short-term consumption of the high-fat diet increased levels of firmicutes bacteria in the gut which are associated with obesity,” said PhD student Vanessa Las Heras.

The effects of diet were also seen beyond the gut, she pointed out.

“This has important implications for human health, especially during pregnancy, in old age and in immunocompromised individuals,” said Dr Cormac Gahan, leader of the research study.

“It also has more general implications for research on infectious disease.”